Belt retractor-belt tensioner-combination with tensioning drive integrated into the belt shaft

ABSTRACT

Disclosed is a self-locking safety belt retractor comprising a blocking element which can be triggered in a belt band-sensitive and/or vehicle-sensitive manner and blocks the rotation of the belt shaft in the unwinding direction of the belt, and a tensioning drive which acts upon the belt shaft and rotates said belt shaft in the winding direction of the safety belt when being triggered. The inventive safety belt retractor is characterized by the fact that the tensioning drive which is provided with two parts ( 14, 15; 26, 32 ) that move relative to each other when said tensioning drive is triggered, is disposed on the belt shaft without being connected to the housing ( 10 ) of the belt retractor and rotates along with the belt shaft before being triggered. Furthermore, one part of the tensioning drive is fixed by means of the blocking element ( 17 ) as an abutment for the tensioning movement of the second part of the tensioning drive when the tensioning drive is triggered.

BACKGROUND OF THE INVENTION

The invention relates to a self-locking seatbelt retractor with ablocking element that can be triggered in a belt-sensitive and/orvehicle-sensitive manner for blocking the rotation of the belt shaft inthe unwinding direction and with a tensioning drive that acts upon thebelt shaft and that, upon triggering, rotates the belt shaft in the windup direction of the security belt.

A seatbelt retractor with the state of the art features is described inDE 196 09 524 A1. In this connection, a tensioning drive is configuredas a pyrotechnic cable tensioner that, upon triggering, sets a driveplate into rotation. The drive plate is connectable with the belt shaftvia a centrifugal force coupling in the form of a radially outwardlydisplaceable rotation acceleration tensioner, so that the rotationalmovement of the drive plate in the belt wind up direction is transmittedover to the belt shaft.

To the extent that there occurs, at the conclusion of the tensioningprocess, a rotation of the belt shaft in the extension direction byreason of the commencing advance shifting of the belted-in passenger,which rotation is to be prevented by the belt retractor-side blockingelement, this known configuration has the disadvantage associatedtherewith that a certain rotational path of the belt shaft in the beltwind up direction is required for a steering in of the blocking elementafter the conclusion of the tensioning movement before the blockingelement is controlled into position and the further withdrawal of theseatbelt is blocked. Additional disadvantages to be noted include thefactor that the configuration of an appropriate coupling between thebelt shaft and the tensioning drive is expensive and, finally, thearrangement of the tensioning drive on the housing of the belt retractorand their fixed connection with one another brings with it acorresponding requirement for space to accommodate this arrangement.

The invention solves the challenge, with respect to a self-lockingseatbelt of the above-noted art, of shortening, in particular for theblocking of the belt shaft following the conclusion of the tensioningmovement, the requisite turn around path that exists until theengagement of the blocking element and, also, solves the challenge ofreducing the size of the belt retractor-belt tensioner-combination.

SUMMARY OF THE INVENTION

The solution to this challenge is set forth in advantageousconfigurations and further embodiments of the invention recited in thesubject matter of the patent claims that follow this description.

The invention provides in its core concepts that the tensioning drive,which comprises two components that are set into relative movementrelative to one another upon the triggering of the tensioning device, isarranged without a connection to the housing of the seatbelt retractoron the belt shaft and rotates in common, before its triggering, with thebelt shaft, and that the blocking element is retained on a firstcomponent that, upon triggering of the tensioning drive, initiallyinitiates a rotation in the pull out direction and is, via the movementof the first component, controlled into its blocking position, and thebelt shaft is connected with the other—namely, the second—component ofthe tensioning drive, which second component is rotated in the wind updirection by reason of the application of the drive force occurring inconnection with the fixedly disposed first component, whereby a reversemovement stop is arranged between the first and second components of thetensioning drive that is continuously effective in the extensiondirection and that runs in a free running condition in the wind updirection. Thus, a significant feature of the invention is that thetotal tensioning drive is integrated in the belt shaft, whereby, tointroduce the tensioning movement, the belt shaft on the otherwiseavailable blocking system of the belt retractor is engaged by theblocking element that is triggered in a belt-sensitive and/orvehicle-sensitive manner in the normal operation of the belt retractor.Thus, a discrete coupling between the tensioning drive and the beltshaft is no longer required.

While during the tensioning driving a movable component coupled with thebelt shaft such as a piston or a rotor is, via the tensioning energythat is typically produced such as, for example, a pyrotechnicallyproduced gas or, as well, an electrical energy, moved relative to afixedly located housing of the tensioning drive that is connected withthe belt retractor housing, the uniqueness of the inventive beltretractor-belt tensioner-combination is more so that the movablecomponent of the tensioning drive that is movable in the unwindingdirection at the beginning of the tensioning process is fixedly lockedto the housing via the blocking element that is retained on this movablecomponent and, thus, this movable component forms the end stop for thesubsequent relative movement that takes the form of a reverse rotationof the “housing” acting in the role of the second component of thetensioning drive in the wind up direction. To this extent, the functionof both components of the tensioning drive changes during the tensioningprocess, because the first component is transformed from a moveablecomponent into a fixedly disposed component and the second component istransformed from, initially, a quasi-fixedly located component into acomponent that transmits the tensioning movement.

A reverse movement stop is provided as the sole additional component,the reverse movement stop being disposed between the first and secondcomponents of the tensioning drive, continuously effective in the pullout direction, and, following the conclusion of the tensioning movement,preventing a reverse rotation of the belt shaft in the extensiondirection. As the continuously effective reverse movement stop does notrequire any steering in or turn around-path, the belt shaft is, at theend of the tensioning process, directly blocked in the extensiondirection by reason of the renewed engagement of the blocking element ina teeth arrangement fixedly set in the housing.

Thus, a further advantage of the invention is that a fixed connectionbetween the tensioning drive and the housing of the belt retractor isnot created. Thus, there is a saving of space and on additionalcomponents and, as well, force flows are avoided because resort is hadto the force flow paths applied on the belt retractor.

In accordance with one embodiment of the invention, it is provided thatthe reverse movement stop is configured as a ratchet stop with a latchthat moves out of ratchet engagement with a tooth arrangement uponrotation in the wind up direction; in this manner, it is ensured thatthe latch remains constantly in engagement with the teeth arrangement toprevent a rotation of the belt shaft in the extension direction, sothat, as well during normal operation of the belt retractor after thebelt-sensitive and/or vehicle-sensitive controlled-in blocking of theblocking element, the force flow is effected via the tensioning driveand the intermediately operated reverse movement stop.

In accordance with a first embodiment of the invention, it is providedthat the tensioning drive is configured as an electro-motor whose statorforms the shaft body that acts as a support for the seatbelt in the roleof the second component and whose rotor that retains the blockingelement is in the role of the first component. In this connection, thestator serves directly as a shaft body onto which the belt of theseatbelt retractor is wound. In the condition of an electro-motor havingno current flow thereto, the rotor and the stator rotate, respectively,in combination with one another, whereby, in the event of abelt-sensitive and/or vehicle-sensitive controlled swinging out of theblocking element rotatably supported on the rotor into its blockingposition by reason of the reverse movement stop that is continuouslyeffective in the pull out direction, there occurs, as well, a blockingof the rotational movement in the pull out direction of the stator inits role as a shaft body.

Insofar as a state of the art seatbelt retractor as described in stateof art-characterizing DE 196 90 524 A1 comprises, in any event, a forcelimiting device configured as a torsion bar, it is herein provided thatthe torsion bar is arranged in the interior of the rotor and isconnected on its one end in a form-fitting manner with a profile headserving as a support for the blocking element retained thereon and isconnected on its opposite end in a form-fitting connection with therotor. In this event, the stator in its role as a shaft body is directlyconnected, via structures designed to give way at a preset forceapplication, with the profile head that supports the blocking element sothat there occurs, in conventional manner via this approach, theblocking of the belt shaft during normal operation of the beltretractor.

In an alternative embodiment of the invention, it is provided that thetensioning drive is configured as a pyrotechnic drive with a housingconnected to a shaft body supporting the belt in the role of the secondcomponent and with at least one drive piece arranged in the housing thatis effective on a drive shaft acting in the role as a support for theblocking element and is flow-contacted by the gas produced from a gasgenerator upon the triggering of the tensioning drive in the role of thefirst component. In this connection, it is provided in accordance with afirst embodiment of the invention that the drive piece is configuredfrom a piston that is flow-contacted by the gas, whereby, for thepurpose of a symmetrical force transmission in the event of atriggering, it can be provided that pistons are respectively arranged onboth sides of the drive shaft in a symmetrical arrangement. While, inconnection with a conventional pyrotechnic drive as described in thestate of the art publication DE 196 09 524 A1, the movement of thepiston relative to the housing of the tensioning drive is converted intowind up movement of the belt shaft, in connection with this inventiveembodiment, the commencing movement of the piston is solely exploited inorder to swing out into its blocking position the blocking element thatis coupled with the piston by the intermediately activated drive shaft.Thereafter, the piston of the tensioning drive is fixedly set in apreset position and the further effect of the gas generated by the gasgenerator leads to a rotation of the housing of the tensioning driveconnected with the shaft body.

To convert the drive movement of the piston into the rotational movementof the driveshaft that retains the blocking element, it can be provided,in accordance with alternative embodiments of the invention, that thedriveshaft and the piston are coupled with one another via meshing teethin a manner such that the linear movement of the piston is, upontriggering of the tensioning drive, converted into a rotational movementof the driveshaft or that there is wound onto the driveshaft a belt thatis guided over the piston and is secured to the housing such that thelinear piston movement leads to an unwinding of the belt from thedriveshaft and, consequently, leads to a rotation of the housingrelative to the fixedly retained driveshaft.

To the extent that the drive piece is configured via a cooperativeworking arrangement of the piston and the belt, it can be provided, inaccordance with an embodiment of the invention, that the deployment ofthe piston is omitted so that the belt is directly flow-contacted. Inthis connection, it is provided, in further details, that a belt iswound onto the driveshaft and a pre-arched chamber, disposed in the pathof the flow of the gas, is closely disposed to the housing such that theflow-contacting of the belt leads to an unwinding of the belt from thedriveshaft and, consequently, a rotation of the housing relative to thefixedly set driveshaft.

Also, in connection with those embodiments of the invention having apyrotechnic drive, the integration of a torsion bar as a conventionalforce limiting device is possible in that the driveshaft is configuredas an inner disposed torsion bar that is driven by the piston at its endarranged relative to the tensioning drive and is connected at itsopposite end with a profile head serving as a support of the blockingelement, whereby the shaft body is connected with the profile head viastructures designed to give way at a preset force application.

It can be provided in an advantageous manner that the gas generator isarranged on a fixedly set cover of the seatbelt retractor and extendswith its gas exhaust region into a partitioned gas space configured inthe housing of the tensioning drive.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the invention are set forth in more detail in thedrawings that are hereinafter described. These drawings show:

FIG. 1 a schematic side view of a seatbelt retractor with an integratedtensioning drive configured as an electro-motor,

FIG. 2 a view of the seatbelt retractor corresponding to that of FIG. 1with an integrated torsion bar,

FIG. 3 a schematic side view of the seatbelt retractor with thetensioning drive configured as a pyrotechnic drive,

FIG. 4 a schematic back view of the housing of the tensioning drive withthe piston arrangement for initiating the triggering of the tensioningdrive,

FIG. 5 a view of the subject matter of FIG. 4 during the tensioningprocess.

DESCRIPTION OF SPECIFIC EMBODIMENTS

The belt retractor-belt tensioner-combination schematically shown inFIG. 1 comprises an U-shaped housing 10 in whose shanks or side legs 11a shaft body is rotatably disposed onto which a belt designated as 13 iswound. To the extent that the tensioning drive illustrated in theembodiment shown in FIG. 1 is configured as an electro-motor, the stator14 of the electro-motor serves as the shaft body supporting the belt 13,the stator forming on a flange 40 on the right side, relative to theembodiment shown in FIG. 1, of the shaft body, the bearing in theassociated shank 11 of the housing 10. The rotor 15 associated with theelectro-motor is arranged in the interior of the stator 14, the rotor,on the end thereof lying opposite to the flange 40, extending outwardlyover the stator 14 and forming, via a flange 41 configured thereat, theother bearing location for the belt shaft bearing. A blocking element 17is rotatably supported on the back side of the shank 11 and iscontrollable into engagement with teeth formed on the shank 11 suchthat, in the condition of the blocking element 17 being outwardly moved,the rotation of the rotor 15 relative to the housing 10 is blocked. Asis not further illustrated and is otherwise known from the respectiveprior art, the blocking element 17 is subjected to a belt-sensitiveand/or vehicle-sensitive steering in during normal operation of theseatbelt retractor. A reverse movement stop is further provided betweenthe rotor 15 and the stator 14 having a latch 19 rotatably supported onthe stator 14 and, in the wind up direction, in continuous engagementwith teeth 18 formed on the rotor 15, whereby free, non-engagingmovement of the latch in the wind up direction permits a relativerotation between the stator 14 and the rotor 15.

In normal operation of the belt retractor, the stator 14 and the rotor15 are rotated by the winding up movement or, respectively, the pull outmovement, of the belt that is transmitted by the rotational movement ofthe shaft body; in the event a swinging out of the blocking element 17rotatably supported on the rotor 15 occurs due to a belt-sensitiveand/or vehicle-sensitive control system, the rotor 15 is fixedly set toexecute its rotational movement in the wind up direction and, by virtueof the reverse movement stop 18, 19 that is, in any event, active in thewinding up direction, the stator 14 in its role as a shaft body isblocked, so that the unwinding movement of the belt 13 is prevented.

In the event of a triggering of the tensioning drive, there occurs aflow of current to the electro-motor initially leading to a rotation ofthe rotor 15 in the belt unwinding direction and, via this rotation, theblocking element 17 is controlled into the teeth associated with theshank 11. Once the rotor 15 is constrained to follow a given path in itsrotational direction, the flow of current to the elector-motor leads tothe condition that the stator 14 rotates in an opposite rotationaldirection—that is, in the winding direction (arrow 36)—relative to thefixedly set rotor 15, whereby, in this relative rotational direction,the latch 19 moves outwardly of the teeth 18 to be in its free,non-engaging movement. After the completion of the tensioning process,the stator 14 serving in its role as a shaft body is, upon an ensuingbelt unwinding movement, coupled via the immediately effective reversemovement stop 18, 19 to the rotor 15 that has been fixedly set in itsposition via the engagement of the blocking element 17, so that nofurther belt unwinding movement is possible.

The embodiment illustrated in FIG. 2 has, in addition, a torsion bar 20integrated into the tensioning drive, the torsion bar being disposed inthe interior of the rotor 15 and being connected, on the side thereof tothe right as shown in the illustration in FIG. 2, to the rotor 15 with aform-fitting connection. On the opposite side thereof, which is to theleft in the illustration in FIG. 2, the torsion bar 20 is connected in aform-fitting manner with a discrete profile head 21 serving as a supportfor the blocking element 17, whereby the profile head 21 is displacedrelative to the rotor 15 and is connected with the stator 14, serving inits role as the shaft body, via a not-herein illustrated but basicallyconventional manner as illustrated in the state of the art publicationDE 196 02 549 A1, namely, structures designed to give way at a presetforce application that are, for example, in the form of shear pins.

The function of the embodiment illustrated in FIG. 2 is, with respect tothe normal operation of the belt retractor, as well as with respect tothe tensioning process, the same as described with respect to thefunctioning operation discussed with respect to FIG. 1. In the eventthat, in normal operation, it comes to a belt-sensitive and/orvehicle-sensitive steering in of the blocking element into its blockingposition, the profile head 21 is fixedly set in its rotation in theunwinding direction. By reason of the connection of the profile head 21to the stator 14 serving in its role as the shaft body via structures 42(see FIG. 3) designed to give way at a preset force application, thestator 14 is also blocked in the unwinding direction. If theelectro-motor is controlled to operate as the tensioning drive, thetensioning process completes itself in the same manner as has beendescribed with respect to FIG. 1, whereby, following the controllinginto position of the blocking element 17 to begin the tensioningprocess, with the beginning of the “reverse rotation” of the stator 14in the winding up direction, the connection between the profile head 21and the stator 14 in its role as the shaft body is lifted via thedestruction of the structures designed to give way at a preset forceapplication. When it now comes, at the end of the tensioning process, toa reversal of the rotational direction of the stator 14 that configuresthe shaft body, the rotation of the stator 14 in the unwinding directionis converted via the reverse movement stop into a rotation of the rotor15 in the same rotational direction, whereby, now, a rotation of therotor 15 relative to the profile head 21, which has been further fixedlyset by the blocking element 17, follows, and this relative movementleads to a corresponding force limiting demand of the torsion bar 20that is activated between the profile head 21 and the rotor 15.

In the embodiment illustrated in FIGS. 3-5, the tensioning drive isconfigured as a pyrotechnic drive, whereby, in this embodiment, atorsion bar is likewise integrated into the configuration as a forcelimiting device. This embodiment can be, to be sure, configured as wellwithout a torsion bar.

The pyrotechnic drive is comprised of a housing 26, which is integrallyconnected as a single piece with a shaft body 25 serving as the supportof the belt 13, so that the housing 26 respectively rotates with theshaft body 25. The shaft body 25 is, thus, rotatably supported in thesame manner as the stator is supported in the embodiment described withrespect to FIGS. 1 and 2 by means of a flange 40 on the associated shank11 of the housing 10. The housing 26 is gripped by a housing cover 28mounted on the shank 11, a gas generator 29 being fixedly mounted on theback side of the housing cover. The gas generator 29 projects with a gasexhaust region 34 into the housing 26, which is configured, in thisregion, with a gas-partitioning space 30.

A wind up spring 37 is disposed between the housing 26 and the housingcover 28, the outer end of the spring being hung on the housing coverand the inner end of the spring being hung on the housing 26 so that thewind-up spring 37 ensures, in a known manner, the reverse rotation ofthe shaft body 25 with the housing 26.

As can be seen in a collective view of FIGS. 4 and 5, two pistons 32 arelongitudinally displaceably arranged within the housing 26 with gaschannels 31 extend from the gas partitioning space 30 thereto so that,in the event of a triggering, the gas produced by the gas generator 29drives the piston 32. As a result, the pistons 32 work together, in astill-to-be described manner, against a shoulder 38 of the torsion bar20 that is the same as that described with respect to the embodimentshown in FIGS. 1 and 2, and that is arranged in the interior of theshaft body 25. A profile head 21 with a blocking element 17 rotatablysupported thereon is disposed on the opposite end of the torsion bar 20,as has been described.

If the above-described belt retractor-belt tensioner-combination isconfigured with the pyrotechnic tensioning drive without the actuationof a torsion bar, an axial drive shaft can be provided in lieu of thetorsion bar, the blocking element 17 being rotatably supported on thisaxial drive shaft so that the drive movement of the piston 32 can betransferred to the blocking element 17 via the drive shaft provided inlieu of the torsion bar 20.

As can be seen in FIGS. 4 and 5, the gas produced by the gas generator29 flows, in the event of a triggering, via the gas channels 31 to thepistons 32, which initially effect a rotation of the torsion bar 20 inthe belt unwinding direction as is shown by the arrow 35. This rotationleads, as described, to a locking of the other end of the torsion bar 20via the profile head 21 and the thereon rotatably supported blockingelement 17. In the event that the torsion bar 20 or, respectively, itsshoulder 38, is fixedly set, the still further effective gas pressureleads to a rotation of the housing 26 in the wind up direction of thehousing 26 shown by the arrow 36 as well as a rotation of the shaft body25 connected therewith, in that, respectively, a belt 33 wound onto theshoulder 38 of the torsion bar 20 and extending therefrom to therespective piston 32 and secured as well to the housing 26 is unwound.

In accordance with a type of recoil principle, there occurs acorresponding rotation of the housing 26. In connection with thisrotation of the housing 26, with the shaft body 25, in the belt wind updirection, the latch 19 of the reverse movement stop correspondinglyprovided on the shaft body 25 moves out of ratchet engagement with thecorrespondingly configured teeth 18 on the torsion bar 20 so that, uponthe conclusion of the tensioning movement, the shaft body 25 is directlyblocked in the belt unwinding direction.

As is not further illustrated, in the embodiment shown in FIGS. 3-5, thearrangement of the pistons 32 can be omitted; it is sufficient, for thedrive movement, that the belt 33 is in a form by which it is connectedto a pre-arched chamber, disposed in the path of the flow of the gas,that is closely disposed to the housing 26; the gas flows into thechamber and directly impacts the belt such that there correspondinglyoccurs a rotation of the torsion bar 20.

The disclosed details of the subject matter of this item as set forth inthe above-described description, the patent claims, the abstract, andthe drawings can be important individually as well as in desiredcombinations for the realization of the invention in its variousembodiments.

The specification incorporates by reference the disclosure of Germanpriority document 102 35 543.6 filed Aug. 3, 2002 and PCT/EP2003/007554filed Jul. 12, 2003.

The present invention is, of course, in no way restricted to thespecific disclosure of the specification and drawings, but alsoencompasses any modifications within the scope of the appended claims.

1. A seatbelt retractor for retracting a security belt windable and unwindable from a belt shaft that is rotatably supported in a housing, the seatbelt retractor comprising: a tensioning drive that acts upon the belt shaft and that, upon triggering, rotates the belt shaft in a wind up direction of the security belt, the tensioning drive including a first component that, upon release of the tensioning drive, initially initiates a rotation in a pull out direction and a second component, the two components being set into movement relative to one another upon triggering of the tensioning drive and the tensioning connection being arranged without a connection to the housing of the seatbelt retractor on the belt shaft and rotating in common, before the triggering of the seatbelt retractor, with the belt shaft; a reverse movement stop is arranged between the first and second components of the tensioning drive; and a blocking element that can be triggered in a belt-sensitive and/or vehicle-sensitive manner for blocking the rotation of the belt shaft in an unwinding direction, the blocking element being retained on the first component and being, via the movement of the first component, steered into its blocking position, the belt shaft being connected with the second component of the tensioning drive, which second component is rotated in the wind up direction by reason of the application of a drive force occurring in connection with the first component that is fixedly disposed, wherein the reverse movement stop is arranged between the first and second components of the tensioning drive and is continuously effective in the extension direction and runs in a free running condition in the wind up direction.
 2. A seatbelt retractor according to claim 1, wherein the reverse movement stop is configured as a ratchet stop with a latch that moves out of ratchet engagement with a tooth arrangement upon rotation in the wind up direction.
 3. A seatbelt retractor according to claim 1, wherein the tensioning drive is configured as an electro-motor whose stator forms the shaft body that acts as a support for the seatbelt in the role of the second component and whose rotor that retains the blocking element is in the role of the first component.
 4. A seatbelt retractor according to claim 1 and further comprising a force limiting device configured as a torsion bar, the torsion bar being arranged in the interior of the rotor and is connected on its one end in a form-fitting manner with a profile head serving as a support for the blocking element retained thereon and is connected on its opposite end in a form-fitting connection with the rotor, whereby the rotor is directly connected with the profile head via structures designed to give way at a preset force application.
 5. A seatbelt retractor according to claim 1, wherein the tensioning drive is configured as a pyrotechnic drive with a housing connected to a shaft body supporting the belt in the role of the second component and with at least one drive piece arranged in the housing that is effective on a driveshaft acting in the role as a support for the blocking element and is flow-contacted by the gas produced from a gas generator upon the triggering of the tensioning drive in the role of the first component.
 6. A seatbelt retractor according to claim 5, wherein the drive piece is configured as a piston that is flow-contacted by the gas.
 7. A seatbelt retractor according to claim 6, wherein, for the purpose of a symmetrical force transmission in the event of a release, it can be provided that pistons are respectively arranged on both sides of the drive shaft in a symmetrical arrangement.
 8. A seatbelt retractor according to claim 6, wherein the driveshaft and the piston are coupled with one another via meshing teeth in a manner such that the linear movement of the piston is, upon release of the tensioning drive, converted into a rotational movement of the driveshaft.
 9. A seatbelt retractor according to claim 6, wherein a belt is wound onto the driveshaft, wherein the belt is guided over the piston and is secured to the housing such that the linear piston movement leads to an unwinding of the belt from the driveshaft and, consequently, leads to a rotation of the housing relative to the driveshaft that is fixedly retained.
 10. A seatbelt retractor according to claim 5, wherein a belt is wound onto the driveshaft and a pre-curved chamber, disposed in the path of the flow of the gas, is closely disposed to the housing such that the flow-contacting of the belt leads to an unwinding of the belt from the driveshaft and, consequently, a rotation of the housing relative to the fixedly set driveshaft.
 11. A seatbelt retractor according to claim 5 and further comprising a force limiting device configured as an inner disposed torsion bar that is driven by the piston at its end arranged relative to the tensioning drive and is connected at its opposite end with a profile head serving as a support of the blocking element, wherein the shaft body is connected with the profile head via structures designed to give way at a preset force application.
 12. A seatbelt retractor according to according to claim 5 and further comprising a gas generator arranged on a fixedly set cover of the seatbelt retractor and extends with its gas exhaust region into a partitioned gas space configured in the housing of the tensioning drive. 